BEIJING -- Chinese authorities have formally arrested a wealthy Chinese businessman who was a key supporter of a civil society group that has been the target of a wide-ranging crackdown this year, his lawyer said Monday.

Beijing prosecutors approved the arrest of venture capitalist Wang Gongquan on Sunday, according to Chen Youxi, Wang's lawyer, who said prosecutors notified him by phone of the decision on Monday.

Wang was detained in mid-September on suspicion of "gathering crowds to disturb public order" but had not been formally arrested until Sunday. The vaguely defined charge has been used to prosecute many members of a loosely organized movement that has been pushing for greater public participation in Chinese political issues.

The notification of Wang's formal arrest underscores the seriousness with which Chinese authorities are treating his case. When prosecutors approve an arrest, it usually indicates that police have gathered enough evidence -- or are in the process of doing so -- to proceed with an indictment and perhaps trial.

Chen declined to comment further, but Chen Min, a veteran journalist and close family friend of Wang's, said the businessman's family had not yet received notice of the arrest.

Wang has been a supporter of the New Citizens Movement, a loose network of activists that has come under official scrutiny this year, with an estimated 30 members rounded up since March.

"Gongquan has mainly been trying to promote efforts to turn this country toward democracy and constitutionalism from the perspective of a citizen," said Chen, who is better known in China by his pen name Xiao Shu. "If these types of actions are deemed intolerable by this country then they are warning all Chinese that this government does not allow its people to be citizens."

The group's members have done little more than lobby for rights of rural children and public disclosure of officials' assets, although they have urged people to hold peaceful street demonstrations and dinner meetings to discuss such issues. Beijing is wary of anything it sees as having the potential to develop into a force that can challenge Communist Party rule.

Beijing prosecutors did not immediately respond to a request for comment.

The arrest comes as the U.N. Human Rights Council prepares to review China's human rights situation on Tuesday in Geneva. China was last reviewed in 2009 by the 47-nation council, the U.N.'s top human rights body, which examines each nation's rights record every four years. This year rights groups have criticized Chinese authorities for tightened controls in Tibet and Xinjiang as well as the ongoing crackdown on civil society.

Foreign Ministry spokeswoman Hua Chunying said in a regular briefing Monday that China would listen to "constructive criticism" raised during the U.N.'s review, but reject opinions that are biased. "Toward the ill-intended and biased criticism, we can only respond that we will maintain our own path, and we will abide by our own judgment," Hua said.